[SystemSafety] [External] Re: Miss vs Ms

[Driscoll, Kevin]

> W&B calculations on commercial aircraft are an example of a critical process
I wonder how well that is internalized and not just “known” by the people that create, maintain, and use the W&B calculation tools and processes.  (“Someone once told me that W&B calculations are critical to safe flight.”)  I can see that easily being lost when all W&B calculations are done in backroom computers at an airline’s operation center, along with a lot of other non-critical airline data processing.  I once saw all NWA planes in the take-off que at SEA get pulled to the side (~90% of the dozen of planes in the que) because their W&B computer (in TN?) went down.

From: systemsafety <systemsafety-bounces at lists.techfak.uni-bielefeld.de> On Behalf Of Nick Tudor
Sent: Tuesday, April 13, 2021 3:54 AM
To: Peter Bernard Ladkin <ladkin at causalis.com>
Cc: systemsafety at lists.techfak.uni-bielefeld.de
Subject: [External] Re: [SystemSafety] Miss vs Ms

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Memory is a little fuzzy and no doubt others may have better. There was an unauthorised use of a spreadsheet to do v1/v2 calculations for an E3 AWACS aircraft some many years ago   I believe that there was an issue with the V1 speed as rotation at too low a speed meant that V2 couldn’t be reached. It ran out of runway.

On Tue, 13 Apr 2021 at 08:11, Peter Bernard Ladkin <ladkin at causalis.com<mailto:ladkin at causalis.com>> wrote:


On 2021-04-13 02:02 , Bruce Hunter wrote:
>
> The interesting thing was that this was indirectly a result of updated software errors in an update
> to the off-board load balancing computer on a PC (ALPAC). Great lesson that dangerous software
> failures may not just occur on integrated systems but on separate ancillary equipment as well. You
> really need to check whether safety functions are dependent on external
systems reliability as well
You sure do.

W&B calculations on commercial aircraft are an example of a critical process in which data and their
accuracy are key. Not only is the SCSC Data Safety Guidance relevant, but
so are other routine
cross-checks well known in computer science.

After an Emirates A340 narrowly avoided becoming a horrendous accident on
takeoff from Melbourne in
2009, Bernd Sieker and I wrote a short note explaining how such data safety procedures, input and
processing, could be improved. (It seems we sent it to HESSD, but I am not sure HESSD was held that
year.)

A decade on, trivial design/programming errors are apparently still making it into such
safety-related software.

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
ClaireTheWhiteRabbit RIP
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